Soil Enzyme Activities And Their Influencing Factors In Different Land Types In Shenbei New District

The problems of urban environment-related soil environmentalquality gradually become prominent with the changes of land use types and utilization direction in the process of urbanization.Soil enzymes are involved in many major biochemical processes performed by soil ecosystems,which activities are commonly used as early warning and sensitive indicators of soil environmental quality and changes in soil ecosystems.In this paper,we studied the characteristics of soil enzyme activitieswith soil micro-organism,soil physical and chemical properties,the relationshipheavy metal forms in soil of Shenbei New District by using the grid layout method combining with soil enzyme activity analysis,high-throughput sequencing and atomic absorption spectrometry.Illustrated typical soil enzyme activity with changes of land use types and the main factors,which aimed to provide data support and theoretical basis for the changes of soil ecological environment in urban expansion areas.Soil enzyme activity analysis showed that the significant differences in soil enzyme activities between different land use types in Shenbei New District.The activities of catalase showed as follows: paddy field> urban green space> natural forest land> dry land;soil phosphatase activity showed as follows: urban green land> dry land > natural woodland> paddy field;however,the changes of soil urease activity were: dry land> natural forest land> urban green land > paddy fields.Theseresults indicated that the changes of soil phosphatase and urease were similar,while the changes of soil catalase activity are opposite to urease and phosphatase.The results of soil microbial community structure analysis showed that there were significant differences in soil microbial diversity among different land use types.There was a significant positive correlation between soil catalase activity and soil microbial diversity index(Chao1).Soil phosphatase activity had a significantly negative correlation with Chao1 index,while urease activity had no significant correlation with Chao1 index.Soil physical and chemical properties analysis showed that soil catalase activity had a significant positive correlation with soil water content and pH(p<0.01),and soil phosphatase activity was extremely significantly negative correlated with soil water content,pH and total phosphorus(p<0.01).There was a significant negative correlation between soil urease activity and soil water content(p<0.01).Soil microbial diversity index(Chao 1)showed a significant positive correlation with soil water content and pH value.Theseresults indicated that the soil water content and pH value was an important environmental factor affecting soil enzyme activity.The analysis results of heavy metals in soil showed that there was no significant correlation between heavy metal content and soil microbial diversity index.However,the activities of soil catalase decreased significantly with the increase of the main contents of Cd,Pb,Cu and Zn.Phosphatase and urease activity also showed a significant correlation with some forms of heavy metal content.Theseresults indicated that heavy metals had some effect on soil enzyme activities.